中国地区卷云消光后向散射比的星载激光雷达遥感

利用两年的星载激光雷达数据对中国地区卷云的消光后向散射比［又称激光雷达比 (简称LR)］进行了研究分析。其中结合多次散射对光学厚度的依赖关系式和LR与透过率之间的关系式来求取LR, 并提出五条质量控制标准来保证数据质量的可靠性。统计结果指出LR的月季变化并不是很明显, 均值在24左右。中国地区的LR在热带辐合带相对较高, 并随纬度的降低而增加 (大约从22到27)。同时, 从这个结论得出, 为了更好地求取卷云的光学厚度, 在中国地区为星载激光雷达选取的LR常数应该随纬度变化而改变。

Extinction to Backscatter Ratio of Cirrus Clouds Retrieved by Spaceborne Lidar over China

The two-year spaceborne lidar data are used to study the extinction-to-backscatter ratio, i.e., lidar ratio (LR), of cirrus clouds over China. The LRs are retrieved by the combination of the equation between multiply scattering factor and optical depth and the equation between LR and transmittance. Additionally, five data quality control standards have been made to assure the high availability. The mean value of LR is 24 without prominent monthly and seasonal variations. The LRs are relatively high in the intertropical convergence zone over China, and increase with latitude decreasing (approximately from 22 to 27). This demonstrates that constant LR should be changed with latitude in order to enhance the quality of retrieval of cirrus cloud optical depth.